Fluorescence Suppression In Raman Spectroscopy And Its Application For Complex Liquid Mixtures

As a modern analysis method,Raman spectroscopy has the advantages of fast speed,strong spectral characteristics and non-destructive measurement.It has been widely used in production processes in recent years.However,fluorescence background seriously affects the application of Raman spectroscopy.For two kinds of typical complex liquid mixtures,Raman spectroscopy fluorescence suppression methods are proposed respectively in this thesis.The main contents are listed below:1.For diesel with complex composition,a combined fluorescence suppression method based on sample processing and numerical calculation is proposed.Some diesel samples have strong fluorescence background,and it is difficult to obtain the effective Raman signal.In this paper,a special sample processing device is designed.The diesel samples with strong fluorescence background are first filtered,and then the numerical calculation method is applied for baseline correction.The results show that this method can improve the signal-to-noise ratio of diesel Raman spectra by more than 12 times.2.For the esterification process of polyester production,online detection of the clear point based on Raman spectroscopy is developed.The esterification reaction mixture is a heterogeneous system,and the reaction is in high temperature.At the same time,its fluorescence background is strong.Therefore,an on-line Raman detection system with 1064 nm laser is set up.According to the principle of esterification reaction,the correspondence between the molecular structure of the reaction mixture and the peaks of the Raman spectra is established.The area ratio of Raman peaks of benzene-loop and ester group is chosen as a characteristic variable,and a rule to determine the clear point of the reaction is established.3.A novel online Raman analyzer is developed.The hardware system is mainly composed of a laser with 1064 nm,a heat-resistant Raman probe and a dispersion InGaAs array spectrometer.The analysis software includes spectral data acquisition and analysis,analysis result output and display,spectral data storage and historical data query.This system has been applied to small experimental equipment for polyester production.